Expose ServerCodecConfigurer as a bean

With this commit, ServerCodecConfigurer is now exposed as a bean in
order to be provided to DefaultServerWebExchange via
WebHttpHandlerBuilder and HttpWebHandlerAdapter. This allows
DefaultServerWebExchange to get configured codecs for reading form or
multipart requests.

Issue: SPR-14546

spring-web/src/main/java/org/springframework/web/server/adapter/DefaultServerWebExchange.java

@@ -34,7 +34,8 @@ import org.springframework.http.HttpMethod;
 import org.springframework.http.HttpStatus;
 import org.springframework.http.InvalidMediaTypeException;
 import org.springframework.http.MediaType;
-import org.springframework.http.codec.FormHttpMessageReader;
+import org.springframework.http.codec.HttpMessageReader;
+import org.springframework.http.codec.ServerCodecConfigurer;
 import org.springframework.http.server.reactive.ServerHttpRequest;
 import org.springframework.http.server.reactive.ServerHttpResponse;
 import org.springframework.util.Assert;
@@ -46,6 +47,8 @@ import org.springframework.web.server.ServerWebExchange;
 import org.springframework.web.server.WebSession;
 import org.springframework.web.server.session.WebSessionManager;
 
+import static org.springframework.http.MediaType.*;
+
 /**
  * Default implementation of {@link ServerWebExchange}.
  *
@@ -56,8 +59,6 @@ public class DefaultServerWebExchange implements ServerWebExchange {
 
 	private static final List<HttpMethod> SAFE_METHODS = Arrays.asList(HttpMethod.GET, HttpMethod.HEAD);
 
-	private static final FormHttpMessageReader FORM_READER = new FormHttpMessageReader();
-
 	private static final ResolvableType FORM_DATA_VALUE_TYPE =
 			ResolvableType.forClassWithGenerics(MultiValueMap.class, String.class, String.class);
 
@@ -85,26 +86,35 @@ public class DefaultServerWebExchange implements ServerWebExchange {
 	 * Alternate constructor with a WebSessionManager parameter.
 	 */
 	public DefaultServerWebExchange(ServerHttpRequest request, ServerHttpResponse response,
-			WebSessionManager sessionManager) {
+			WebSessionManager sessionManager, ServerCodecConfigurer codecConfigurer) {
 
 		Assert.notNull(request, "'request' is required");
 		Assert.notNull(response, "'response' is required");
-		Assert.notNull(response, "'sessionManager' is required");
-		Assert.notNull(response, "'formReader' is required");
+		Assert.notNull(sessionManager, "'sessionManager' is required");
+		Assert.notNull(codecConfigurer, "'codecConfigurer' is required");
 
 		this.request = request;
 		this.response = response;
 		this.sessionMono = sessionManager.getSession(this).cache();
-		this.formDataMono = initFormData(request);
+		this.formDataMono = initFormData(request, codecConfigurer);
 		this.requestParamsMono = initRequestParams(request, this.formDataMono);
+
 	}
 
-	private static Mono<MultiValueMap<String, String>> initFormData(ServerHttpRequest request) {
+	@SuppressWarnings("unchecked")
+	private static Mono<MultiValueMap<String, String>> initFormData(
+			ServerHttpRequest request, ServerCodecConfigurer codecConfigurer) {
+
 		MediaType contentType;
 		try {
 			contentType = request.getHeaders().getContentType();
-			if (MediaType.APPLICATION_FORM_URLENCODED.isCompatibleWith(contentType)) {
-				return FORM_READER
+			if (APPLICATION_FORM_URLENCODED.isCompatibleWith(contentType)) {
+				return ((HttpMessageReader<MultiValueMap<String, String>>)codecConfigurer
+						.getReaders()
+						.stream()
+						.filter(messageReader -> messageReader.canRead(FORM_DATA_VALUE_TYPE, APPLICATION_FORM_URLENCODED))
+						.findFirst()
+						.orElseThrow(() -> new IllegalStateException("Could not find HttpMessageReader that supports " + APPLICATION_FORM_URLENCODED)))
 						.readMono(FORM_DATA_VALUE_TYPE, request, Collections.emptyMap())
 						.switchIfEmpty(EMPTY_FORM_DATA)
 						.cache();

spring-web/src/main/java/org/springframework/web/server/adapter/HttpWebHandlerAdapter.java

@@ -21,6 +21,7 @@ import org.apache.commons.logging.LogFactory;
 import reactor.core.publisher.Mono;
 
 import org.springframework.http.HttpStatus;
+import org.springframework.http.codec.ServerCodecConfigurer;
 import org.springframework.http.server.reactive.HttpHandler;
 import org.springframework.http.server.reactive.ServerHttpRequest;
 import org.springframework.http.server.reactive.ServerHttpResponse;
@@ -38,6 +39,7 @@ import org.springframework.web.server.session.WebSessionManager;
  * then invokes the target {@code WebHandler}.
  *
  * @author Rossen Stoyanchev
+ * @author Sebastien Deleuze
  * @since 5.0
  */
 public class HttpWebHandlerAdapter extends WebHandlerDecorator implements HttpHandler {
@@ -46,6 +48,8 @@ public class HttpWebHandlerAdapter extends WebHandlerDecorator implements HttpHa
 
 	private WebSessionManager sessionManager = new DefaultWebSessionManager();
 
+	private ServerCodecConfigurer codecConfigurer;
+
 
 	public HttpWebHandlerAdapter(WebHandler delegate) {
 		super(delegate);
@@ -71,6 +75,24 @@ public class HttpWebHandlerAdapter extends WebHandlerDecorator implements HttpHa
 		return this.sessionManager;
 	}
 
+	/**
+	 * Configure a custom {@link ServerCodecConfigurer}. The provided instance is set on
+	 * each created {@link DefaultServerWebExchange}.
+	 * <p>By default this is set to {@link ServerCodecConfigurer#create()}.
+	 * @param codecConfigurer the codec configurer to use
+	 */
+	public void setCodecConfigurer(ServerCodecConfigurer codecConfigurer) {
+		Assert.notNull(codecConfigurer, "ServerCodecConfigurer must not be null");
+		this.codecConfigurer = codecConfigurer;
+	}
+
+	/**
+	 * Return the configured {@link ServerCodecConfigurer}.
+	 */
+	public ServerCodecConfigurer getCodecConfigurer() {
+		return this.codecConfigurer != null ? this.codecConfigurer : ServerCodecConfigurer.create();
+	}
+
 
 	@Override
 	public Mono<Void> handle(ServerHttpRequest request, ServerHttpResponse response) {
@@ -87,7 +109,7 @@ public class HttpWebHandlerAdapter extends WebHandlerDecorator implements HttpHa
 	}
 
 	protected ServerWebExchange createExchange(ServerHttpRequest request, ServerHttpResponse response) {
-		return new DefaultServerWebExchange(request, response, this.sessionManager);
+		return new DefaultServerWebExchange(request, response, this.sessionManager, getCodecConfigurer());
 	}
 
 }

spring-web/src/main/java/org/springframework/web/server/adapter/WebHttpHandlerBuilder.java

@@ -22,6 +22,7 @@ import org.springframework.beans.factory.NoSuchBeanDefinitionException;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.context.ApplicationContext;
 import org.springframework.core.annotation.AnnotationAwareOrderComparator;
+import org.springframework.http.codec.ServerCodecConfigurer;
 import org.springframework.http.server.reactive.HttpHandler;
 import org.springframework.util.Assert;
 import org.springframework.util.ObjectUtils;
@@ -51,6 +52,7 @@ import org.springframework.web.server.session.WebSessionManager;
  * {@link #applicationContext(ApplicationContext)}, or a mix of both.
  *
  * @author Rossen Stoyanchev
+ * @author Sebastien Deleuze
  * @since 5.0
  * @see HttpWebHandlerAdapter
  */
@@ -62,6 +64,9 @@ public class WebHttpHandlerBuilder {
 	/** Well-known name for the WebSessionManager in the bean factory. */
 	public static final String WEB_SESSION_MANAGER_BEAN_NAME = "webSessionManager";
 
+	/** Well-known name for the ServerCodecConfigurer in the bean factory. */
+	public static final String SERVER_CODEC_CONFIGURER_BEAN_NAME = "serverCodecConfigurer";
+
 
 	private final WebHandler webHandler;
 
@@ -71,6 +76,8 @@ public class WebHttpHandlerBuilder {
 
 	private WebSessionManager sessionManager;
 
+	private ServerCodecConfigurer codecConfigurer;
+
 
 	/**
 	 * Private constructor.
@@ -102,6 +109,8 @@ public class WebHttpHandlerBuilder {
 	 *	ordered.
 	 *	<li>{@link WebSessionManager} [0..1] -- looked up by the name
 	 *	{@link #WEB_SESSION_MANAGER_BEAN_NAME}.
+	 *  <li>{@link ServerCodecConfigurer} [0..1] -- looked up by the name
+	 *	{@link #SERVER_CODEC_CONFIGURER_BEAN_NAME}.
 	 * </ul>
 	 * @param context the application context to use for the lookup
 	 * @return the prepared builder
@@ -126,6 +135,14 @@ public class WebHttpHandlerBuilder {
 			// Fall back on default
 		}
 
+		try {
+			builder.codecConfigurer(
+					context.getBean(SERVER_CODEC_CONFIGURER_BEAN_NAME, ServerCodecConfigurer.class));
+		}
+		catch (NoSuchBeanDefinitionException ex) {
+			// Fall back on default
+		}
+
 		return builder;
 	}
 
@@ -184,6 +201,16 @@ public class WebHttpHandlerBuilder {
 		return this;
 	}
 
+	/**
+	 * Configure the {@link ServerCodecConfigurer} to set on the
+	 * {@link ServerWebExchange WebServerExchange}.
+	 * @param codecConfigurer the codec configurer
+	 */
+	public WebHttpHandlerBuilder codecConfigurer(ServerCodecConfigurer codecConfigurer) {
+		this.codecConfigurer = codecConfigurer;
+		return this;
+	}
+
 
 	/**
 	 * Build the {@link HttpHandler}.
@@ -199,6 +226,9 @@ public class WebHttpHandlerBuilder {
 		if (this.sessionManager != null) {
 			adapted.setSessionManager(this.sessionManager);
 		}
+		if (this.codecConfigurer != null) {
+			adapted.setCodecConfigurer(this.codecConfigurer);
+		}
 
 		return adapted;
 	}